Normal hair can be so fine and limp, and so lacking in body that the hair does not hold a hair set well. Furthermore, the hair can become even less bodied and can be weakened further as a result of being subjected to chemically active hair treatments, such as permanent waves and tints. Additionally, hair can be weakened even further by other contributing factors, such as bleaching by sun exposure and/or chlorinated swimming pool water.
Hair setting is basically the process of shaping wet hair by the steps of stretching the hair by curling the hair, fixing the hair in place by drying, then combing to give the finishing touches to provide the desired hair style. In particular, the setting of wet hair can be accomplished by making flat curls from strands of hair and fixing the curls with hairpins to produce "pin curls". Similarly, the wet hair can be set by using any of a variety of rollers or curlers to mechanically fix the hair. In either case, the winding of the wet hair is followed by drying, either by ambient air drying, electric drying or hot air drying.
The inherent problem encountered in hair setting is the natural tendency of the hair to return to its natural shape. For example, the set hair returns to its natural shape almost immediately if moistened. Likewise, high humidity conditions accelerate the tendency of the hair to return to its natural shape. Therefore, intensive efforts have been directed toward providing a hair set with sufficient holding power to maintain the designed hair style until at least the next shampoo, and, therefore, giving the hair set a degree of permanency.
Therefore, investigators have sought to delay the combined action of natural forces and moisture that causes the hair to return to its original state by applying solutions containing naturally-occurring or synthetic polymers after the hair is shaped into a desired configuration. When applied to the shaped hair from aqueous or aqueous/alcoholic solutions (setting lotions), the polymers leave a film on the hair, after drying, to help maintain the hair in the previously shaped configuration. The polymeric film promotes cohesion and gives stability to the hair set to maintain the hold of the hair set. The principal objective of a setting lotion is to cover the previously styled hair with an invisible polymeric film that will give the styled hair a degree of rigidity and protect the hair style against wind and humidity.
Hair spray products act in a similar manner. The hair spray products are applied to wet and/or dry hair and contain a polymer, or mixtures of polymers, that remain fixed on the previously styled hair and affect the hair in various ways. For example, a "mechanical" effect is exerted on each individual hair. The film-forming polymers are used to provide a flexible sheath of polymeric film on the shaped hair after drying and, therefore, for mechanical reasons, retard the return of each individual hair to its natural shape. In addition, the polymeric film provides an overall stiffening of the hair and the hair strands are welded together, and the final hair style has better cohesion, therefore resisting the natural forces that return the hair to its natural shape. Finally, the polymeric film protects the hair from humidity. The ability of the polymeric film to attract and absorb water is preferably minimal, such that the polymeric film retards moisture uptake by hair and retards the return of the hair to the natural configuration.
The general principles of hair setting are thoroughly discussed by C. Zviak, in The Science of Hair Care, Marcel Dekker, pp. 149-181 (1986). Zviak reviews both the polymers used in hair setting products and the formulation principles used to produce a hair set product that provides such beneficial hair set properties as improved hair style hold, easy application and combing, quick drying and non-stickiness, good hair body and bounce, increased hair volume and gloss, and hydrophobicity.
The prior art reveals that nonionic, cationic and anionic polymers have been used in hair set products, with the anionic polymers providing the best hair set results. However, anionic polymers also have disadvantages, such as high water-solubility and, therefore, low hydrophobicity, and low substantivity to hair fibers, therefore, easy elimination from the hair by combing and brushing. As a result, investigators have continued to search for compounds and compositions that provide the primary benefit of an improved durability of the hair set. As previously mentioned, to overcome some of the inherent disadvantages of the polymers utilized to set the hair, hair set products are made available in diversified forms in an attempt to minimize the drawbacks of the particular polymer used in the formulation. For example, hair set products are available as plasticizing lotions, plasticizing gels, aerosol foams, all-purpose lotions, hair sprays, and holding lotions.
Others have attempted to polymerize monomers, in-situ, while in contact with hair, as discussed in "Polymerization Into Human Hair", Robbins, et al., Journal of Society of Cosmetic Chemists, Vol. 25, pp. 407-421, August, 1974; "Modification of Hair By Internal Deposition Of Polymers", Wolfram, Journal of Society of Cosmetic Chemists, Vol. 20, pp. 539-553, Aug. 19, 1969; and U.S. Pat. Nos. 3,472,604; 3,676,550; 3,634,022 and 4,588,760. The monomers have been problematic due to the tendency of the monomeric materials to be irritating and/or harmful to the hair and/or skin of the user, particularly absorption of harmful monomers into the skin of the user, and of the harsh feel left in the hair or hair discoloration. Further, the reduction of hair prior to treatment generally is necessary and causes additional damage to the hair.
A major deficiency in prior art polymer hair treatments is the lack of durability of these treatments, usually washing out after one or two shampoos. The in-situ polymerization in accordance with the present invention provides a desirable polymer that lasts at least through three shampoos. While other researchers have attempted to improve the durability of polymer treatments by forming the polymer in-situ, the main drawback to these previous treatments was that toxic and/or irritating monomeric species were used. One patent, Breuer U.S. Pat. No. 4,278,659 discloses the application of an oligomer formed by the condensation reaction of glyceraldehyde and resorcinol heated together in the presence of boric acid or silicic acid that only partially polymerizes the monomers. One of the problems with the application of the oligomeric composition disclosed in U.S. Pat. No. 4,278,659 is that the pH of the composition must be at or below about 1.6 to achieve the polymerization of the monomers due to the necessity of the acid addition, requiring later alkali addition for raising the pH to an acceptable level before the composition can be safely applied to the hair. Another problem with the oligomeric composition disclosed in U.S. Pat. No. 4,278,659 is that a substantial quantity of monomer that has not polymerized is left in the composition. Resorcinol becomes pink upon exposure to light and air and significant absorption into the skin through the scalp or hands can cause health problems, or even death. Accordingly, until the present invention, there has been no safe and effective oligomeric hair care composition or method of applying an oligomeric composition to hair and further polymerizing the oligomer while in contact with the hair.
U.S. Pat. No. 4,682,612 discloses oligomers such as urethane-acrylates that are photoinitiated in the formation of artificial nails as long as positive benefits are conferred to the hair. Any of the oligomers disclosed in U.S. Pat. No. 4,682,612 are useful in accordance with the present invention so long as the monomer is not harmful to the skin and the U.S. Pat. No. 4,682,616 is hereby incorporated by reference.
In accordance with the present invention, a new and improved aqueous, alcoholic or hydroalcoholic composition, or compositions containing other cosmetically acceptable solvents, and methods have been found wherein a safe polymerizable oligomer or prepolymer composition having essentially no irritating or harmful monomers and/or oligomeric materials, is applied to wet or dry hair and, thereafter, the hair is processed to polymerize the oligomer, in-situ, while in contact with the hair, to further polymerize the oligomer(s) or prepolymer(s). The oligomer(s) or prepolymer(s) are polymerized in-situ, e.g., with a thermal appliance, such as a blow dryer or a curling iron, and/or by including a polymerization accelerator or polymerization catalyst in the composition, or in a separate composition. Polymerization, in-situ, without the presence of toxic, hazardous or harmful monomer(s) or oligomer(s), has substantial advantages over application of a completely polymerized polymer or polymerization of an oligomer mixed with toxic or hazardous monomer(s) since in-situ polymerization enables the oligomer to be in contact with the hair during the various polymerization stages for better chemical attachment to the hair while minimizing the possibility of the absorption of harmful monomers into the user's skin. Further, in-situ polymerization provides substantially increased body to the hair; provides better uptake of polymer onto the hair; provides a polymer coating with less flaking; can provide a more complete attachment of the resulting polymer to the hair; better protects the hair against uptake of humidity; strengthens damaged hair; resists removal through at least three shampoos; are useful to make permanent waves more durable without reducing agent odor; prevents leach out of hair colors; can provide for higher loading of polymer into and onto the hair and, therefore, better set retention; protects the hair against thermal damage and better resists hair uptake of atmospheric contaminants.